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SSS 2010-12-02

时间:2011-01-06 05:58来源:互联网 提供网友:tianshun   字体: [ ]
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    (单词翻译:双击或拖选)

This is Scientific American's 60-Second Science, I'm Christopher Intagliata. Got a minute?

Life on earth requires six basic ingredients—carbon, hydrogen, nitrogen, oxygen, sulfur1 and phosphorus. Those six elements are the building blocks for DNA2 and RNA, along with proteins and fats. Which means they're essential for life—as we know it. But it might be time to update that list. Because scientists have found a bacterium3 that can do without phosphorus—live on arsenic4 instead.

Researchers had a hunch5 a bug6 like this might exist because arsenic has some chemical properties in common with phosphorus. So they collected mud from California's Mono Lake, where the waters are naturally salty, and laced with arsenic. Back in the lab, they cultured microbes from that mud. But instead of adding phosphorus to the cultures to help the bugs7 grow, they added varying levels of arsenic.

One bacterial8 strain continued to thrive. And tests confirmed that the organisms compensated9 for the lack of phosphorus by building their DNA with arsenic instead. The research appears in the journal Science. This is the first known life form that seems to be able to swap10 out one of life's fundamental building blocks with another element. So for astrobiologists hunting for life in space, don't rule out places filled with poison.

Thanks for the minute. For Scientific American's 60-Second Science, I'm Christopher Intagliata.


点击收听单词发音收听单词发音  

1 sulfur ps4wC     
n.硫,硫磺(=sulphur)
参考例句:
  • Sulfur emissions from steel mills become acid rain.炼钢厂排放出的硫形成了酸雨。
  • Burning may produce sulfur oxides.燃烧可能会产生硫氧化物。
2 DNA 4u3z1l     
(缩)deoxyribonucleic acid 脱氧核糖核酸
参考例句:
  • DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
  • Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。
3 bacterium BN7zE     
n.(pl.)bacteria 细菌
参考例句:
  • The bacterium possibly goes in the human body by the mouth.细菌可能通过口进入人体。
  • A bacterium is identified as the cause for his duodenal ulcer.一种细菌被断定为造成他十二指肠溃疡的根源。
4 arsenic 2vSz4     
n.砒霜,砷;adj.砷的
参考例句:
  • His wife poisoned him with arsenic.他的妻子用砒霜把他毒死了。
  • Arsenic is a poison.砒霜是毒药。
5 hunch CdVzZ     
n.预感,直觉
参考例句:
  • I have a hunch that he didn't really want to go.我有这么一种感觉,他并不真正想去。
  • I had a hunch that Susan and I would work well together.我有预感和苏珊共事会很融洽。
6 bug 5skzf     
n.虫子;故障;窃听器;vt.纠缠;装窃听器
参考例句:
  • There is a bug in the system.系统出了故障。
  • The bird caught a bug on the fly.那鸟在飞行中捉住了一只昆虫。
7 bugs e3255bae220613022d67e26d2e4fa689     
adj.疯狂的,发疯的n.窃听器( bug的名词复数 );病菌;虫子;[计算机](制作软件程序所产生的意料不到的)错误
参考例句:
  • All programs have bugs and need endless refinement. 所有的程序都有漏洞,都需要不断改进。 来自《简明英汉词典》
  • The sacks of rice were swarming with bugs. 一袋袋的米里长满了虫子。 来自《简明英汉词典》
8 bacterial dy5z8q     
a.细菌的
参考例句:
  • Bacterial reproduction is accelerated in weightless space. 在失重的空间,细菌繁殖加快了。
  • Brain lesions can be caused by bacterial infections. 大脑损伤可能由细菌感染引起。
9 compensated 0b0382816fac7dbf94df37906582be8f     
补偿,报酬( compensate的过去式和过去分词 ); 给(某人)赔偿(或赔款)
参考例句:
  • The marvelous acting compensated for the play's weak script. 本剧的精彩表演弥补了剧本的不足。
  • I compensated his loss with money. 我赔偿他经济损失。
10 swap crnwE     
n.交换;vt.交换,用...作交易
参考例句:
  • I will swap you my bicycle for your radio.我想拿我的自行车换你的收音机。
  • This comic was a swap that I got from Nick.这本漫画书是我从尼克那里换来的。
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